Identifying Sources of Error in Computer-Navigated Total Knee Arthroplasty Using Sensitivity Analyses in Knee Models

Area of Science:

• Orthopedic surgery
• Medical device technology
• Surgical navigation systems

Background:

• Computer-assisted total knee arthroplasty (TKA) has not consistently shown superior outcomes compared to conventional methods.
• Potential errors in navigated TKA include surgeon variability in landmark registration and cutting guide placement.
• Identifying and quantifying errors at critical steps is essential for improving navigated TKA procedures.

Purpose of the Study:

• To identify the sources of error during computer-navigated total knee arthroplasty (TKA).
• To quantify the impact of these errors at each critical procedural step.
• To assess the influence of landmark registration accuracy on TKA outcomes.

Main Methods:

• Utilized sawbones and 3D-printed knee models for error assessment.
• Digitized landmarks with a navigation system and concurrently recorded points with a 3D capture system.
• Quantified errors using transformation matrices (metric on SE(3)) and performed Monte Carlo simulations for sensitivity analyses.

Main Results:

• Largest registration errors were observed at the hip center (8.2 ± 4.4 mm) and lateral tibial plateau (4.8 ± 3.7 mm).
• Femur center exhibited the least variability (0.8 ± 0.5 mm) and was identified as the most critical landmark for registration accuracy.
• Errors in femoral and tibial center landmarks significantly influenced bone reference frames, with broader tibial errors (5.8 mm) compared to femoral errors (1.3 mm).

Conclusions:

• Landmarks closer to the knee joint in navigated TKA have narrower safe zones and greater impact on system accuracy.
• The lack of correlation between bone reference frame errors and cut plane errors indicates additional error sources.
• Enhanced intraoperative strategies, including advanced imaging, refined algorithms, and improved training, are necessary to optimize landmark registration and TKA outcomes.